slacken-v; 2 Senses

Sense Number 1: make or become less intense, slow down

Examples:
M3 growth may have slackened in May.
Unfortunately, rules have slackened to the point of ridiculousness.
The rain had slackened to a steady shower and we grabbed Frank.
The evening rush hour on the route has slackened to a trickle.

Sense Number 2: make or become less taut or severe

Examples:
The headtube angle was slackened to 69 degrees.
The arrangement enables the screws to be slackened to release a part welded grid.
I slackened the locks and pointed the scope manually at a couple of easy targets.